/*End of non delimiter tokens*/
/* I have limited the delimiter tokens by eliminating, interval strings
and delimited identifiers BNF and simplifying the legal character set to
the characters to a single set so no identification of character set would
be needed decision. */
<delimiter token> ::= <character string literal>
| <SQL special character>
| <not equals operator>
| <greater than or equals operator>
| <less than or equals operator>
| <concatenation operator>
| <double greater than operator>
| <right arrow>
| <left bracket>
| <right bracket>

TXT Model

This section presents the UML model which describe the interface and implementation of TXT parser.

Interface

This diagram presents the package interface. The parser's methods perform the parsing of TXT predicates and expressions and builds the filter.

Implementation

Below, the figure shows the principal class of the parser and build process implementation. TXTParser does a top down analysis of the input string and makes the parsing tree. Each time TXTParser builds a node, it calls the TXTCompiler, which implements the semantic actions related and builds the product or subproduct required to make the Filters and Expressions at the end of the parsing process.